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 67 LeMans 400ci Question
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RonW
Buffalo

44 Posts

Posted - 18 Feb 2013 :  12:24:20 AM  Show Profile  Reply with Quote
Hi Guy's,

I've been away for quite some time and haven't done much with my 67 LeMans for quite awhile.

I was told by the guy I bought the car from that it has a 67 GTO drive train. 400ci with 670 heads (as noted on the heads), a Comp magnum 280H cam with a Performer intake, Holley 750, Hooker Super Comp headers. Turbo 400 w/shift kit and a 3.73 posi.

I have no idea what compression it has, although it sound pretty healthy, rumptey cam sound at idle.

I don't know if the block is zero decked or what pistons it has, so it could be over 10:1 compression or more.

So here are my questions:

Can I tell by checking the cranking pressure , if this motor is safe to run on pump gas?

I have a set of 4X-7H heads I could use, could I get enough compression for that cam?

Should I just pull the motor and start with a better combo?

I have a 750cfm Q-Jet built by Cliff Ruggles, I've been waiting to install.

Do I need a Performer RPM with that cam or would I need porting to fully utilized the carb, cam.

Is the Performer intake adequate?

Thanks for any info,
Ron

Cobrabill
Talking Dog

Aruba
3128 Posts

Posted - 18 Feb 2013 :  10:54:45 AM  Show Profile  Reply with Quote
If you have a Cliffjet-put it on.The Performer is marginally better or just equal to the factory manifold.Get the distributer done and start tuning.

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Phil
The Great White Buffalo

USA
7219 Posts

Posted - 18 Feb 2013 :  11:32:25 AM  Show Profile  Reply with Quote
And watch for detonation with those 670 heads on pump gas.

Bowties are for Pee-wee Herman. "Chevy": even the name sounds cheap, but not as cheap as your Pontiac will be with an LS transplant.

Edited by - Phil on 18 Feb 2013 1:49:37 PM
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 18 Feb 2013 :  12:27:05 PM  Show Profile  Reply with Quote
280h http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1197&sb=2
Looks like that cam needs the extra compression.
IMO that cam in a 400 is close to the edge for streetable drivability.
The 670 heads are said to have a relitivly good flo rate and are correct for that year modle.
The preformer rpm is probably a better match for that cam and may give you a bit more top end charge. I dont think hood clearance is a issue on that car. Someone holler if im mistaken.
If the cliff carb is set up FOR THAT COMBO then by all means use it.
Alot of power can be gained or lost at the distributor.
Hotrod combo's can be finicky and time consuming to get dialed in.
If your combo runs good/strong after warmed up then drive it.
Other than intake and distributor you probably wont get significant power gains without expensive head and block modifications.
If your combo runs good/strong after warmed up then drive it.
-In my opinion-



Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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RonW
Buffalo

44 Posts

Posted - 18 Feb 2013 :  3:57:36 PM  Show Profile  Reply with Quote
The car has not run in over 5 years. So I have to drop the gas tank and clean the fuel system, before I try to fire it up.

I basically bought the car and parked it, other issues got in the way until now.

I don't have any stated goal for the car, just have some fun with it at the 1/8 mile here locally and make it look good.

Cliff originally built the Q-jet for a 455. It's still wrapped in the plastic Cliff sent it in.

I have ton's of room for a Performer RPM manifold, I'll be patient and try to find a used one.

I think my first priority should be a new torque converter. Any suggestions on stall?

Comp Cams recommends 2500 rpm with low gears and headers. I have 3.73's and Hooker Super Comp headeres.

After that, any recomendations on intial timing and full advance RPM?

The car is not a daily driver so I don't mind using some 100 octane race gas. Is 50/50 safe or do I need to go 100% ($9.98 per gallon) out here.

Thanks for everyone's input,

Ron




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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 18 Feb 2013 :  10:40:11 PM  Show Profile  Reply with Quote
Im sure cliff would be happy to recomend and order a continental torque converter for your aplication. Also answer questions about your carb. He is an active member here at PSP so go to members and scroll down till you find him. click send an email.
Sounds like your car and engine combo will be a GOOD saterday night racer. I'll keep my fingers crossed and hopefully that thing will start and run good.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Vid
Kicking Horse

USA
1685 Posts

Posted - 20 Feb 2013 :  02:33:54 AM  Show Profile  Reply with Quote
Nice car, Ron. Sounds like some fun is ahead of you!

Some of your questions are going to be trial and error, like how much race gas to blend. I'd say start on the high side (65-75%) and work down with each tankful until you hear ping under load and then increase the mix a little to eliminate the ping. I run a somewhat similar combo (400 with 62 heads) and I mix 35-40% race gas (110 VP leaded). How you tune it will have a big impact on the octane requirement as well. If I could keep my foot out of the throttle, I might could get by on 91 gas (91 is premium gas here in CA) but that's not gonna happen, is it LOL

The cranking pressure doesn't indicate the static compression (I wish it did) but I can tell you mine is right around 190 psi on every cylinder which I *think* is on the high side of normal. Some here on the board have even seen 210+ so who knows.

You have a good carb, Cliff's carbs are highly revered, but check the gaskets and rubber parts to make sure they haven't dried up over that 5 years time.

As for room under the hood, I think you could try a Roots blower on top and still have clearance

Since it's been sitting for so long, besides flushing the fuel tank I'd suggest changing brake fluid and coolant too, checking all the belts and hoses, and the tires for dry rot... check the fuel pressure because the diaphragm could have weakened...

Glad to see your project coming back to life!
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RonW
Buffalo

44 Posts

Posted - 20 Feb 2013 :  1:51:06 PM  Show Profile  Reply with Quote
Vid,

Thanks for your input.

I figured on starting with straight 100 octane until I get the timing and advance figured out. Then I'll reduce to 3 to 1 (3 gal 100 octane and 1 gal 91 octane) and then maybe 50/50 after that.

I planned on going through the brakes to. Gotta be able to stop!

The power steering pump is missing its pulley and will most likely leak, but I'll be fixing that.

It needs tires all the way around and I'll change the hoses and coolant for sure.

Would you advise pulling the distributor and priming the engine before I start it up?

Any thoughts on the Magnum 280H single pattern cam? I was thinking about using 1.65 rockers on the exhaust side only for more duration.

I realize I'll probably have to pull the 670 heads to elongate the push rod holes. At least I could see if the block is decked or if the pistons are dished.

Should I change the cam and put the low compression 4X-7H heads on it if the pistons aren't dished? I can probably get the compression up to around 9:1 with the 4X heads.

Is there a better cam for the 670 heads's at over 10:1 compression?

Mostly looking for power not cruising, I guess I do have a stated goal. LOL

Thanks again, Ron
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Vid
Kicking Horse

USA
1685 Posts

Posted - 20 Feb 2013 :  11:48:06 PM  Show Profile  Reply with Quote
Even though pulling the diz just to pre-oil is kind of a pain, I like the idea only because it's been sitting so long. If not that then maybe change the oil to light weight, fast flowing 5-20 to deliver a shot of lube fast on start up. Maybe turn it by hand (breaker bar on the crank snout) nice and easy for a few revolutions just to get it used to the idea of spinning under power again, LOL

As for the compression and cam options, you've got some homework to do there. The thing to do first is pull at least one of the heads, see what you've got in terms of pistons (dish, flat etc), measure the deck clearance which has a huge impact on the static compression ratio (and detonation, too) and also cc the chambers, this will give you the critical info you need to make a good decision on the cam. There are online compression calculators galore so plug in your numbers and there you go.

The Comp 280 is quite close to my current cam, which is the Comp Magnum Muscle (51-314-4). I think it's an okay cam, nice and healthy sounding for cruising, but performance wise - meh . The revs from idle climb really S L O W and it seems to peak and flatten out pretty early in the rpm band instead of pulling hard and producing that strong, glorious upper mid and top end power. There are surely better grinds out there. My suggestion is to first find your true static compression because in Cam Land that is the first step in a happy marriage.

The 3.73's should be plenty of gear, but what about your converter? If it's stock you definitely want to look into an upgrade there. I bought a Hughes 2500 stall from Summit and the 2500 stall rating is a joke. I'd say it's 2000 if I'm lucky and that may be one of the reasons I'm not real happy with the cam.

You've got your Cliff Q-Jet, headers and 3.73's so you're good there. I don't think the intake manifold is going to make a huge difference no matter which one you choose because they all seem to be pretty good. Stock iron, Performers (regular and RPM), Torkers (I and II) and the old Holley Street Dominators all have their fans here at PSP.

Good luck and keep us posted Ron! Race season, warm weather and long daylight hours are just around the corner, I for one can't wait!
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Brian R
Crazy Horse

USA
1672 Posts

Posted - 21 Feb 2013 :  12:07:22 AM  Show Profile  Reply with Quote
Good idea to pull the distrib and pre-oil it.

Other than that, the 670's will give you similar compression to the 16's I used to run (I believe). With no dish in the pistons you will probably be in the 10:1 to 10.5:1 range. It will need very careful tuning and if lucky it will run decent on 93 octane. Higher octane would be better.

Prime the oil and start it up. Run a couple tank fulls of 93 through it, get your timing right and see how she runs. Don't bother with octane boosters as they are a complete scam. Most are toluene which is 114 octane. A pint of 114 into a tank of 93 is barely a spit in the ocean. For toluene to work you would need 3 or more GALLONS to bring it up to 96 - 98 octane. That's why the octane boosters are all a complete scam.

Best of luck and talk to Cliff and Sixty8 on here. He helped me a lot with my last engine.
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Vid
Kicking Horse

USA
1685 Posts

Posted - 21 Feb 2013 :  12:52:04 AM  Show Profile  Reply with Quote
Right about octane boosters Brian. They all put in BOLD print on those brightly colored bottles that it "Raises octane 2 to 3 points". The average guy buys a bottle and thinks his 92 octane fuel is now 94 to 95. What he's really got is 92.2, or 92.3 at best, for his $9 to $14 investment.

I like using 110 VP Leaded race gas for blending with unleaded pump premium. It's slightly less expensive than 100 octane unleaded, and I can use less of it. My motor is happy with 94 to 95, so about 4 gallons of 110 to 16 gallons of 91 in a 20 gallon tank. I just bought some 110 leaded and it was about $8 per gallon, so it costs me $32 for 4 gallons of 110 and it nets 95 octane. BTW, in California, 91 is "premium".
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RonW
Buffalo

44 Posts

Posted - 21 Feb 2013 :  11:25:51 AM  Show Profile  Reply with Quote
When I was a kid I would have just done whatever it took to get it fired up and start hot-rodding it. Common sense and caution be dammed. LOL
A little wiser now, but still having to fight the urge to hear it run again.
I think I'd better pull a head a see what I've got.
In the end I'm sure it will be time well spent and a huge return on time invested vs a few fun passes and a blown motor.
Thanks for everyone's input, very much appreciated.
I'll let you all know what I find.
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 21 Feb 2013 :  11:26:01 AM  Show Profile  Reply with Quote
Move the engine by hand first to c if it's rusted stuck.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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Vid
Kicking Horse

USA
1685 Posts

Posted - 22 Feb 2013 :  02:52:36 AM  Show Profile  Reply with Quote
quote:
Originally posted by RonW

Common sense and caution be dammed. LOL



Oh, wait... common sense? Does common sense have anything to do with any of this Pontiac stuff?!
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RonW
Buffalo

44 Posts

Posted - 24 Feb 2014 :  4:50:08 PM  Show Profile  Reply with Quote
Still having trouble finding time to work on my car, but I decided to go ahead and pull the motor, to see what I really have.

In the mean time I have been thinking seriously about changing to a 4" stroke crank, with BBC 6.88" rods making it a 433ci.

Why not go with a 4.21 or 4.25 stroke? I'm thinking the 4" crank will be a little stronger and with the 6.88" rods, I'll have the 1.7 rod to stroke ratio, that is supposed to be ideal.

Using some of what I already have, here is my build plan:

400 block (already have) with ARP head and main studs
4" cast crank with forged BBC 6.88" rods
Forged pistons with 23cc dish for 9.52:1 compression
670 heads (already have) self-ported per Jim Hands book
Comp Magnum 280H cam .480 lift, 230 dur @ 0.050" (already have)
1.65 roller tip rockers .528 Lift
Edelbrock Performer RPM intake
Cliff Q-Jet (already have)
Hooker Super Comps (already have)
MSD 6AL with HEI
Turbo 400 with shift kit (already have)
10" Continental torque converter 2800 rpm stall
3.73, 12 bolt posi (already have)

I would appreciate any thoughts on estimated performance/power output or improvement suggestions?

Thanks, Ron
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RonW
Buffalo

44 Posts

Posted - 12 Sep 2017 :  12:02:14 AM  Show Profile  Reply with Quote
Here I go again, saying I'm ready to get started on this car.
Except this time I really did.

I recently had a set of Edelbrock 72cc D-Port heads built to off set the potential compression/detonation problems I thought I might encounter.

Unfortunately, the worries I had about too much compression are no longer an issue.

The motor was supposed to be a rebuilt 67 GTO 400 and it may very well be, it's a YS code block, but it has 8 valve relief cast pistons (17cc I read). I'm under the impression these are just everyday replacement pistons.

That puts my compression at 9.5: 1 if the pistons are .010" in the hole. I may as well use the 72cc 670"s now.


Another issue I found that I don't understand at all, is the block is chamfered for valve clearance. Like they did on 350's with big valve heads, I believe.

Am I wasting my time with this block?
Thanks for any input.
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 14 Sep 2017 :  11:51:44 AM  Show Profile  Reply with Quote
The camfer will improve the air fuel curtain, valve to cylinder wall clearance, and improve intake air flow into the bore.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.

Edited by - Blued and Painted on 14 Sep 2017 11:55:12 AM
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RonW
Buffalo

44 Posts

Posted - 14 Sep 2017 :  8:16:58 PM  Show Profile  Reply with Quote
Thanks for your reply. Sounds like you think the chamfer's are a good thing?
The chamfer's are 1-1/2" wide and 1/4" deep at the widest point on the circumference of the bores.
I was concerned they are pulling the compression down. Any idea how many cc's they might account for?
There also doesn't seem to be any negative effect on the head gaskets.
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 16 Sep 2017 :  2:18:27 PM  Show Profile  Reply with Quote
72 cc alunimum heads at 10.5 to 1 is the norm for 400's. The camphers were standard in 67 with the hi compression 670's if I recall correctly.
An extra point of compression is needed for the extra heat dispersion of the alunimum.


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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RonW
Buffalo

44 Posts

Posted - 16 Sep 2017 :  11:42:00 PM  Show Profile  Reply with Quote
I've read the pistons I have with 8 valve reliefs, are OEM replacement pistons for use in early and later engines. Supposedly they have 17cc in the valve reliefs and the chamfered around the edge of the piston.
Calculated compression with those pistons and .020" in the hole, even with 72cc iron heads it's only 9.11:1.
Putting the new aluminum heads I just bought on it would be the equivalent of 8:1 compression. And then I would always be worried one of those cheap pistons breaking and damaging my new aluminum heads.
I think I'm going to just pull the motor and build the 433ci I really wanted. I never really wanted a 400ci anyway. I was just going to get running while I did other work on the car. Oh well..
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Blued and Painted
Chief PONTIAC

USA
3407 Posts

Posted - 17 Sep 2017 :  1:03:27 PM  Show Profile  Reply with Quote
The 8 eyebrow pistons have plenty of sharp edges to increase tendency for detonation .
The big bevel around the top edge of the piston creats an aria where the air/fuel mixture is trapped and may or may not burn in the power stroke


Bull Nose Formula/ 461/ Q-Jet/
TH400/ 3.08 8.5 / R44TS.
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